I can only assume Mario's earth is at least twice as large as ours, the same certainly holds true for the DC comics' earth.
As for the Koopalings, they'd just take away opportunities for original bosses, and they'd never have dialogue or develop personalities. And if they did they'd probably go in the drive-you-up-the-wall direction, like seven times the Bowser Jr.
A) Giant enemy drones as bosses are not original.
B) You can't prove that the Koopalings couldn't be made more original than a bunch of giant enemy drones.
Here, let me put some food in your brain:
Larry KoopaThe middle child. Rather mischievous, destructive and rebellious. Suitable given that he likes punk rock a lot. Spends all his time playing his guitar, which doubles as a sound-based weapon.
Iggy Koopa Second youngest. He inherited the smart gene. That is to say, he's a genius, both magical and scientific. He's the one who built the mechs in Yoshi's Safari, and always has some sort of mechanical device up his proverbial sleeve. When he's cornered, he usually resorts to throwing noxious potions at you, since he's physically weak.
Lemmy KoopaThe youngest, and also the least competent. He'd much rather run away to join the circus that help his father conquer the Mushroom Kingdom. Still, his agility and balance is unmatched and usually he tries to mess with your head by playing mind games. He may very well drive you crazy if you spend too much time with him alone.
Wendy O. KoopaBowser's little girl, and a spoiled brat to boot. She thinks her singing voice is marvelous, but it's actually loud enough to kill your eardrums. She also specializes in high-fashion, specifically the kind meant for hurting you. Those rings she wears on her arms act as boomerang projectiles and constrictors.
Morton Koopa Jr.He's the fat one, and a pretty big grouch. When he isn't eating, he's usually complaining about something. He also has a soft spot for punk rock like Larry, which is why he's modeled his look after Paul Stanley. Sometimes he uses his drum set as a weapon, other times he inhales huge breathes of air or streams of water and tries to spit it at you.
Roy KoopaThis kid is a beast. The biggest and the strongest, but not the smartest. He isn't very good at speaking properly. Works out a LOT. Whenever he fights he could likely take you out with one punch, and he shakes the ground whenever he jumps.
Ludwig von KoopaThe scary one. Mostly hangs out in the darkest parts of the castle playing his organ. Speaks with a thick German accent probably picked up from his organ instructor. Highly unpredictable in combat, and may resort to any dirty tactics possible, even going so far as to copy his siblings or his father's techniques. Wants to usurp the throne, very badly.
See, how was that? A lot of it is based on what I've read in promotional material, a little of it is from my own imagination in way that adds to said promotional material. I could easily see this being the norm in Paper Mario at least.
